Sliding door mechanism



June 27, 1961 J. A. szczl-:PANIK 2989'771 sLIDING DooR MECHANISM Filed Sept. 22, 1958 3 Sheets--Shee1'l '1 BWVMM TTORNEY June 27, 1951 J. A. szczEPANlK SLIDING DOOR MECHANISM 5 Sheets-Shee-t 2 Filed Sept. 22, 1958 zNVENTQR. John Aszczeponlk ATTORN E Y United States Patent O 2,989,771 'SLIDING DOOR John A. Szczepanik, Brooklyn, N-Y., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Sept. 22, 1958, Ser. No. 762,558 3 'Claims. (Cl. 16-88) This i-nvention relates to lift mechanisms having roller elements for the lifting and sliding operation on horizontal door tracks of lift doors such as are used for railway box cars, and more partcularly to an improved lift mechanism, each roller element of which provides a plurality of balls operatively positioned around an inner race Vwithin a vertically disposed raceway. The raceway is formed by a ball cage having an open bottom section to allow the weight of the door to be supported upon the balls which rotate freely between the bottom surface of the inner race and the track during the lifting of the door, and which circulate around the inner race when the door is moved along the track to its open or closed position.

Because of the heavy weight of side doors used in railway box cars and because of necessarily rough treatment of the cars and the doors and their use in all kinds of weather, a suitable lift mechanism for such doors must provide strength and simplicity of construction for ease in fabrication, installation and maintenance and as much freedom as possible from friction in the lifting and sliding movements of the lifted door upon the door track. When, as is most usual, a lift mechanism employs two roller elements mounted at the lower corners of the door, there should be uniform lifting of the door above the track to prevent strain as well as to provide facile operation.

ln the normal operation of a lift door, and particularly after rough or extensive use, its path along 'a door track may deviate slightly from the straight line of travel because of misalignment of or irregularities in the track or door. In some instances -it may be forced to travel transversely within mechanically imposed limits Vduring its opening or closing operation. When Wheels are used as roller elements these deviations cause strain, restrct free movement of the door and contribute yto theobreakdown of the lift mechanism. The use of separate castings and housings for Wheels and the systems of bars, levers and links for simultaneous lifting Operations of the door around the Wheels as well as maintenance and replacement of wo'rn parts present further problems attendant with the use 'of this type of lift mechanism.

In ball supported lift doors, which have the advantage of being more freely movable in all directions, only single ball roller elements have been employed in the past. These lift mechanisms become ineflicient if 'a ball becomes defective through use. a Such ball supported lift doors have had further disadvantages arising from the necessity of maintaining spaced relationship between a plurality of single ball roller elements and between the balls and the door. Restraining mechanisms, extraneous to the lifting and sliding operation of the door, have been employed to` keep the balls 'and their connecting means pressed in position against the door track while the door is in down position and itsweight off the balls. It is advantageous to employ as many balls as possible for distribution of the weight of thepdoor. and increase in antifriction action by permitting pure rolling of the balls. V

However, the number of single ball roller elements 'used 'its objects and advantages.

2`,989`,7 71h Patented June 27, 1961 ice in lift mechanisms in the past has been restricted because of available space at the lower margin of a lift door and the necessity of individually housing each ball or ythe complexity and weakness of connecting mechanisms and restraining means for keeping spaced relationships. A further disadvantage of single ball roller elements is that the free rolling of the single ball is hampered by the restraining action of its particular housing or positioner.

In the lift mechanism of the present invention, each roller element comprises a plurality of balls operatively positioned within a vertically disposed raceway formed by arball cage having an open bottom section. The inner race of the raceway is mounted upon the sides of the cage which may be extensions of a single unit ball cage carriage positioned along the lower margin of a lift door and which may support at least one other ball cage. The lower surface of the inner race is fiat and provides a horizontal surface of sufiicient length for it to rest upon more than one ball. As the carriage is positioned along the lower margin of the door and as the bot-tom section of the ball cage is open, the balls upon which the inner race rests are in direct contact with the door track which is mounted on the car horizontally along the lower margin of the door opening for supporting the door. The ends of the ball cage carriage are pivotally linked in lifting relationship with the door. While the door is being lifted by the application of leverage to causevside- Wise movement of the single unit ball cage carriage, its Weight rotates around and presses upon the roller element of the lift mechanism. The balls upon which the inner race rests receive the weight of the door and each provides rotational movement between the inner race and the track for lifting the door. When the door 'is in lift position the balls between the raceway and the track provide complete support for the weight of the door. During the sliding movement of the door along the track, the track acts as an outer race and the balls circulate with pure rolling around the inner race because of their rotational and translational movement between the door and the track. Therefore, all of the plurality of balls in the roller element are utilized for movement along the track and at any given time at least two of the plurality of balls provide rotational movement between the ,door and the track. As the balls are allowed to roll freely around the inner race, the movement of the door along the track is completely free of friction due to ball positioners or other retaining means ordinarily present in ball supported lift doors. The balls of the lift mechanism of this invention are guided and kept within the open cage by the cage sides which are in close spaced relationship with and curve along a portion of the lower hemisphere of the supporting balls and 'are pinched slightly inwardly but without clasping of the balls while retaining the same.

These roller elements may readly be used for side car doors not of the lift type for sliding the door along a track. The advantages of the roller elements are equally applicable to such doors except rotational action of the 'balls for lifting is not required.

Having described generally the lift mechanism of the invention the following description of a specific embodiment of the invention will serve to make more apparent Reference will be made to the accompanying drawings of which:

FIVGURE 1 is a side elevation of a railway box car indicating generally the position of the lift mechanisml of 3 the invention relative to the lift door supported on the car;

FIGURE 2 is a fragmentary horizontal section partly broken away taken along the lines of 2-2 of FIGURE l showing the lift door in closed position;

-FIGURE 3 is a fragmentary side elevation partly broken away of the car showing the lift mechanism in its housing at the lower margin of the lift door, the front plate of the housing having been removed;

FIGURE 4 is a fragmentary plan view of the lift mechanism;

FIGURE 5 is a fragmentary longitudinal section partly broken away of the lift mechanism showing the door in lowered position upon the door track;

FIGURE 6 is a fragmentary longitudinal section partly broken away of the lift mechanism showing the door in lift position above the door track;

FIGURE 7 s a transverse section partly broken away taken along the lines 7-7 of FIGURE 5 and showing a transverse section of the lift mechanism housing;

FIGURE 8 is a transverse section partly broken away taken along the lines 8-8 of FIGURE 6 also showing a transverse section of the lift mechanism housing;

FIGURE 9 is a transverse section partly broken away taken along the lines 9-9 of FIGURE 4;

FIGURE 10 is a transverse section partly broken away taken along the lines 10-10 of FIGURE 1.

The drawings show a railway box car 1 which is provided with a lift door, indicated generally at 2, mounted upon a door track 3 which is secured to the car below an angle member 4, the horizontal leg of which is the lower rim of the door opening.

The door comprises a rectangular metal door plate 5 paneled on its outer surface by a horizontally positioned box girder 6 which assists in supporting and is retained within the U-shaped front marginal member 7 of the door at its front end and the rear marginal member 8 of the door at its rear end. The lower extension of the door plate provides the inner wall of the lift mechanism housing which is positioned along the lower margin of the door and extends out from the door past the outer legs of the front and rear marginal members of the door. The front and rear portions of the outer section 9 of the housing, adjacent the front and rear ends, taper inwardly to the ends which are retained by the front and rear `marginal members of the door in the same way as the ends of the box girders. A cover plate 10 is utilized to provide access to the lift mechanism and when in place is positioned over the cut-out portion, indicated at 11, in the top section 12 of the housing and over the cut-out portion indicated at 13 of the outer section of the housing. The bottom section 14 of the housing comprises a substantially U-shaped strip. The horizontal section of the U is the lower rim of the door and provides openings, indicated at 15, to allow the balls 16 of the lift mechanism to support the mechanism on the track. Along the inner Vertical leg of the lower marginal member there are provided brackets 17 which assist in guiding and keeping the door upon the track during its opening and closing operation by cooperating with the Vertical leg of the angle member threshold plate 4 shown in the drawings as having angle reinforcement and retainer strips 18 and 19. The upper marginal member 20 of the door comprises an inverted U-shaped flange which cooperates with an opposed U- shaped flange 21 of an angle member 22 to guide the door during its opening and closing operation and to keep the door from `falling in toward or out from the car. The angle member 22 is shown in FIGURE 10 to be secured to the top retaining member or side plate 23 of the car, the lower Vertical leg of which provides the upper rim of the door opening. The small angle member 24 positioned along the outer edge of the horizontal section of the retainer forms a gutter or water shed in the door Zone of the car.

The track is secured to the car just below the lower rim of the door opening and is reinforced by angle brackets 25 for transferring weight imposed upon the track to the side of the car.

When the door is in closed and lowered position the lower rim and the entire weight of the door rests upon the door track. The front marginal member of the door is wedged into the U-shaped flange 26 of the front door stop shown in FIGURE 2 as being reinforced by a Z-shaped strip 27. The strip and the stop are secured to the car adjacent the outer edge of the front rim 28 of the door opening. The rear marginal member of the door is provided with a flange 29 which extends at an angle forwardly toward the car to form a catch for the spark strip 30 secured to the car adjacent the outer edge of the rear rim 31 of the door opening.

The lift mechanism is shown positioned upon the door track within the housing along the lower margin of the door. It presents a single unit ball cage carriage having a center housing for the leverage system of the lift mechanism and front and rear end extensions each of which comprises an outer cage side 32, 321 and an inner cage side 33, 331.

The opposing surfaces of the ends of the cage sides are provided with bearings for journaling a pivot pin 34, 341 for rotational movement of the lower section of a link 35, 351 the upper section of which is pivotally mounted on a pivot pin 36, 361 journaled in opposing bearing plates 37, 371 and 38, 381 which are secured to the door plate and housing cover plate respectively at a point above and rearward of the center or pivot of the lower section of the link.

The cage sides at either end of the carriage extend to- Ward the center housing, converge toward one another and are fixedly positioned on either side of the front and rear tie plates 41, 42.

The tie plates eXtend rearward and frontward respectively and are secured between the converging end extensions of the inner and outer sides 43, 431 of the center housing.

Within the center housing of the carriage an actuator bar 44 is fixedly mounted on a pivot pin 45 by means of a key. The pin 45 is journaled in bearing plates 46, 47 secured to the door plate and housing cover plate respectively. The outer end of the pivot pin 45 extends through an opening indicated at 48 provided in the outer side of the carriage center housing, through the bearing plate 47 and housing cover plate to provide an operative attaching head 49 for a lever or lift handle 50. The inner end of the pivot pin 45 extends through a corresponding opening in the inner side of the carriage center housing indicated at 51 and is journaled in the bearing plate 46 secured to the door plate. Upper and lower circular bearings 52, 53 are located in Vertical spaced relation adjacent the rear margin of the actuator bar and between the top and bottom edges of the sides of the carriage center housing and are mounted on rotatable bearing pns 54, 55 journaled in bearings provided in the sides of the carriage center housing. The rims of the openings 48 and 51 are correspondingly curved at the front and rear and flat at the bottom and top and are of sufiicient area to allow movement of the carriage with relation to the pivot pin 45 without interference. During the lifting operation, the position of the pin changes from lower rear to a point just rear of upper center of the openings. This change in relative position of the pin and openings is shown in FIGURES 5 and 6.

Each roller element of the lift mechanism shown in the drawings comprises a vertically disposed raceway in which a plurality of balls 16 are operatively positioned for circulation in a Vertical plane around an inner race 56, mounted on the cage sides which together with the retainer cover 57, comprise the ball cage within which the balls operate. To eliminate friction between the balls, they are loosely positioned around the inner race. Each ball cage has an open bottom section indicated at 58 through which the balls project. The lower edges of the cage sides and the opposing ends of the retainer cover extend below the center of the 'balls which at vany'time may be supporting theilift mechanism. To guide and keep the 'balls within the ball cage while the door is being moved to open or closed position, or when the door is being installed or removed the lower edges of the sides 'are slightly curved toward one another curving along a portion of the lower hemisphere o f the'balls between the raceway and the track 'but without effecting a claspi'ng of the balls.

During fabrication or repair the balls may be fed into or removed from the cage through a suitab-le opening in the retainer cover which may be closed by the securing on of a plate over the opening. Since the balls support the weight of the door between the track and the bottom surface of the inner race, great strength in the construction of the retainer cover is not required and the providing of such an opening will not aifect the operation of the roller element.

When it is desired to lift the door to slide it open or closed, the lift handle is moved either to the right or to the left. The actuator bar 44 is thereby forced against either one of the circular bearings and rearward movement of the ball cage carriage is eifected.

The links, connecting the door to the carriage, oppose the rearward movement of the carriage with the weight of the door and its frictional engagement with the door track. Since the links are pivotally connected to the door and to the carriage, the top section of the links being positioned above and rearward of the lower sections, the opposing 'force of the door, in giving way to the rearward urging of the carriage, Will force the door upward and around the pivots of the links and around the roller elements of the lift mechanism. It is seen then that the lifting of the door will be assisted by the rotational movement of the balls, now supporting the door between the inner races and the track.

The lifting of the door is stopped before the link is allowed to adopt a perpendicular position by the coming into contact of the lower edges of the cage sides and the upper surface of the lower rim of the door. 'Ihe stop action is most clearly seen in FIGURE 6. The operator of the door who will have moved the lift handle in the direction in which the door is to be moved may now move the door along the track. With the weight of the door now pressing upon the balls upon which the inner race is supported, movement of the door along the track will efi'ect further rotational movement of the balls between outer race, that is, the track and the inner race causing the balls to circulate around the inner race and bringing into play all of the plurality of balls for every complete cycle of rotation. In the roller elements shown, three balls in each element may be in supportiug and rotational position at any given time during the sliding movement of the door. When the door has been moved to the desired position, the operator releases the lift handle and the door is returned to lowered position by the force of its weight.

In the lift mechanism of the invention, because of the free rolling of the balls around the inner race of each roller element, friction, ordinarily present in ball supported lift doors due to ball positioners or space retainers, is eliminated With a resulting increase in ease of operation and maintenance. With the provision of an inner race with a flat horizontal surface for positioning on the supporting balls a number of balls may be used for distribution of Weight and increase in antifriction action between the weight of the door and the track without the necessity of using separate housings or excessive retaining means. Since the balls circulate around the inner race during the movement of the door along the track a defective ball will not immediately necessitate repair and may not even be perceptible in the over-all operation of the roller element.

The lift mechanism of this invention offers strength and simplicity of construction both in the compact and 'durable construction of the roller element and in the provision of a novel ball cage carriage fabricated as a single unit. By providing the single unit cage carriage the simple linkage arrangement at the end extensions of the carriage assures uniform lifting of the weight of the door around the roller element.

Various changes in the details and construction of the lift mechanism of the invention may be made without departingfromV its spirit and scope. It is therefore intended to limit the scope of the invention only by the following claims.

What is claimed is this:

1. A lift mechanism for lifting and sliding a door along a track, said track providing a broad flat longitudinally extending upper surface, said door providing a longitudinally extending lower margin overlying said track, said lift mechanism comprising a rigid ball cage carriage extending longitudinally adjacent said lower margin of said door and formed with ends and a center portion intermediate said ends, means rigidly connecting said center portion and said ends, opposing side walls forming part of said ends, said opposing side walls being vertically disposed in spaced apart relation and extending longitudinally above said track, ball retainer means interposed between and secured to said opposing side walls at either said end, each said ball retainer means and said opposing side walls forming a vertically oriented raceway and having an open bottom section formed by the lower edges of said retainer means and said opposing side walls, an inner race mounted by and secured to said opposing side Walls within each said ball retainer means and providing an elongated and longitudinally extending undersurface, a plurality of balls operatively positioned around said inner race within said retainer, those of said plurality of balls underlying said longitudinally extending undersurface of said inner race supporting the same by projecting downwardly through said open bottom section and bearing on said upper surface of said track, lever means, pivot means mounting said lever means on said door adjacent the lower margin thereof, said pivot means extending freely through said center portion of said ball cage carriage, means rigidly secured on said ball cage carriage and abutting said lever means radially of said pivot means and longitudinally spaced therefrom, lin-k means disposed forwardly and further link means disposed rearwardly of said center portion, said link means and said further link means each extending upwardly in inclined parallel relationship to each other and providing a lower end and an upper end, and further pivot means, said further pivot means mounting one said end of each said link means on said door adjacent said lower margin, and mounting the other said end of each said link means on said ball cage carriage ends.

2. A ball cage carriage, said ball cage carriage extending longitudinally and comprising, spaced ends, a center portion intermediate said ends, said ends forming opposing side walls, said side walls being Vertically oriented and transversely spaced apart in parallel relationship, a ball retainer cover for each said end, each said ball retainer cover being interposed between and secured to said opposing side walls at either said end and being vertically oriented and having an open bottom section, an inner race for each said end, said inner race being mounted by and connected to said opposing side walls at either said end a'nd within each said ball retainer cover, a plurality of balls operatively positioned around each said inner race, said opposed side Walls and said retainer cover forming a ball cage at either said end of the carriage and having an open bottom section, the lower edges of said opposing side Walls and said retainer covers forming a converging rim for said open bottom section to retain said balls therein, said converging rim extending along a portion of the lower hemisphere of References Cited in the file of this patent UNITED STATES PATENTS 308,916 Moore Dec. 9, 1884 534,964 McCabe Feb. 26, 1895 565,915 Mclntyre Aug. 18, 1896 8 Masterson Dec. 21, 1897 Wentworth Nov. 27, 1900 Thompson Mar. 11, 1930 Klausmeyer et al Oct. 11, 1932 Thies Oct. I8`l 1932 Ionkhof .Tu'ly 11, 1933 Wasberg Oct. 19, 1937 Ditchfield Dec. 21, 1937 Beauchamp Dec. 24, 1940 Greenspon et al May 17, 1955 FOREIGN PATENTS France Apr. 6, 1925 UNITED STATES :PATENT OFFICE CERTIFICATE OF CORRECTION Patent No -.l 2.989.771 June 27, -l961 John A. Szczepanik It is hereby Certified that error ppears in the above numbered patent requiring correction and that the said Letters Patent should read as '-corrected below.

Column 7, line 3, for the ola'ir reference numeral ."l" read 2 Signed and sealed this 2lst day of November 1961,

I (sEAf) Attest:

oERNEsT w. SWIDER DAVID L. LADD Commissioner of Patents Attesting Officer v uscoMM-Dici 

